Pour depressed microcrystalline wax



2,875,082 PoUn nnrnnsssn WCROCRYSTALLINE wax John D. Tench, ProspectPark,

. Pa., assignor to Sun Oil Philadelphia,

Company, .Pa., a corporation of New Jersey No Drawing. Application July18, 1955 r 1 Serial N0. 522,830 7 1 Claims. (CL 106-270) This invention.relates to wax compositions, and is more particularly directed tomicrocrystalline waxeshavmg a minor quantity of a pour depressantincorporated therein.

Microcrystalline waxes derived from petroleum are well known tempts havebeen made to surface of the mold in turn impresses a wrinkled surface onthe metal or metal alloy cast thereon. The resulting metal casting mustthen surface. n

An object of the present invention is to provide a new microcrystallinewax composition. Another object is to provide a microcrystallinewaxcomposition especially suitable for use in producing molds which can beused for the precision casting of metal articles. Other objects will beapparent from the following specification.

It has now been found that the incorporation ofa minor. quantity ofv awax of petroleum origin yields a microcrystalline. wax compositionwhichachieves the above and other objects. Thus, the microcrystalline waxvention form a smooth, wrinkle-free surface when solidified from:themoltenstate. The resulting smooth surface renders t he newWaxcornpositions; especially suitable for the preparation of m M ing tifmetal articles. Since the surface imparted to the mold by the-wax issmooth,.the surface of the resulting metal casting issmooth and does notrequire machining.

By pour depressant, as used herein, is meant a material which, whenadded in minor quantity to a lubricating oilhaving a relatively highpour point, such as a paraffinic lubricating oil, substantially reducesthe pour point thereof. The pour point of an oil indicative of thelowest temperature at which it can be poured from a container, and canbe determined by ASTM Method D97-47.

Microcrystalline waxes which can be used to prepare the compositions ofthe invention are derived from the heavy fractions of petroleum,residual fractions producing especially suitable waxes. Themicrocrystalline waxes which can be used should have a melting point ofat least 135 F., andpreferably of at least 150 F., say from about 150 F.to 198 F. The viscosity of the microcrystalline wax should be aboveabout 65 SUS at 210 F. The oil content of the wax should be less thanabout and is preferably less than about 2%. The microcrystalline waxesare generally prepared by dewaxing n petroleum residuum fraction.Advantageously this is and have been employed for many uses; At

bemachined to achieve a smooth 2,875,082 Patented Feb.

accomplished by dissolving a petroleum residuum fraction in a dewaxingsolvent such as methyl ethyl ketone, and chilling the resulting solutionto a relatively low temperature, say from about 5 F. to -20 F., toprecipitate a major portion of the wax therefrom. The resultingmicrocrystalline wax can advantageously be subjected to additionaldeoiling steps such as by further dissolution in a solvent andcrystallization at a relatively low "temperature, or by repulping thewax in a solvent and separating the wax from solvent;

The entire portion of the microcrystalline wax so prepared can beemployed to prepare the composition of the IHVE IItl OH, or any fractionseparated therefrom such as by fractional crystallization, and blends ofsuch fractions,can be used. It is especially advantageous to use blendsof microcrystalline wax having different physicalproperties, such asdifferent melting points, in order to obtain specifically desiredproperties of the final wax product, in addition to the ability of thefinal wax cornposition of the invention to. form smooth surfaces.

Pour depressants are well known,

I thereof can be used in the compositions of the present pour depressantin a microcrystalline compositions of the in- 1 olds forthe precisioncast- I invention. Pour depressants especially suitable for preparingthecomposition's of the present invention are prepared by condensing aderivative of paratlin wax with an aromatic compound. For example,paraifin wax can be chlorinated and the chlorinated wax condensed withan aromatic compound such as naphthalene, toluene, benzene, phenol,phthalic anhydride, or the like, using the Friedel-Crafts reaction.Aluminum chloride is an especially good catalyst to employ but othercatalysts known to be effective in such reactions, such as ferricchloride, stannic chloride, and the like, can be used. Also, if desired,a solvent such as a hydrocarbon naphtha; ethylene dichloride or the likecan be used. The poor depressants can also be prepared by dechlorinatingchlorinated wax and condensing the resulting unsaturated material withthe same aromatic hydrocarbons, i. e., with naphthalene, toluene,benzene, phenol or phthalic anhy tibn are advantageously prepared byincorporating from" about 0.05 to 1.5%

by weight of the pour depressant therein. Incorporation is convenientlyaccomplished by blending the pour depressant into the wax while the waxis in the molten state.

Toillustrate the preparation of the compositions of the invention, amicrocrystalline wax was prepared from a petroleum residuum fractionboiling above about 590 F. at 25 mm. of mercury pressure which had beendeasphaltized and selective solvent extracted. The fraction wasdissolved in a dewaxing solvent consisting of about equal volumes ofmethyl ethyl ketone and benzene, with a small amount of toluene, and theresulting solution chilled to about ---16 F. Wax precipitated at thistemperature was separated from the solution. The resulting wax wasdissolvedat an elevated temperature in a dewaxing solvent consistingessentially of about equal parts of methyl ethyl ketone and benzene. Theresulting solution was cooled to about F. and the wax precipitated atthis temperature was separated by filtration. This and a wide range 'WaxA warn Properties:

' Melting point F. (AS'lM Dl27-49) 193 170 Viscosity at 210F. BUS (ASTMD446-3 85 83 Penetration at 77 F. (ASIM D55 2) 7 .6. 20

A blend containing equal parts by weight ofWax A and Wax B was prepared.To a portion of this blend, while molten, was added 0.5% by weight of apour depressant prepared by condensing chlorinated parafiin wax withnaphthalene by the Friedel-Crafts reaction using aluminum chloride asthe catalyst. The propertiesv As will be observed from the above table,the addition of the pour depressant does not significantly alter theproperties of the wax blend; However, the surface characteristics arecompletely different. In order to'observe the surface characteristics ofthe wax compositions, each composition was cast in a metal mold and thesurface solidifying in contact with air observed. Thissurface should besmooth, since it is often used to reproduce a side ,of a desired metalarticle, and hence it is contacted with the material usedto prepare themold for subsequent preparation of the article. The blend containing thedepressant had a smooth surface and was an excellent material for thepreparation of molds for use in precision metal casting; metal articlesso-prepared present a smooth surface and hence generally do not requireadditional operations such as machining or grinding. The surface of theblend without the depressant was wrinkled, i. e., the surface wasrugose, with serpentine lines forming irregular depressions in the wax,so that the wax com-. position was not suitable for the preparation ofmolds for use in precision metal casting, since metal articles soprepared require additional operations, such as grinding or machining,to achieve a smoothlsurface,

The wax compositions of the invention can be used for purposes otherthanthe preparation of molds for metal casting, such as in uses where asmooth surface or coating of a microcrystalline wax is desired. Forexample, the wax compositions are advantageously used for coating cheeseand meat products, for the preparation of wax figures and-wax toys, andas dentalwaxes.

except that the composition, on solidifying from molten state, forms asmooth, wrinklefree surface. H

Other materials can be' incorporated in the waxzto obtain desiredproperties. For example, paraffin wa'x,

synthetic waxes, a natural wax such as beeswax or carnauba wax, polymerssuch as polyethylene or polyisobutylene, and the like can be addedto themicrocrystalline wax-pour depressant blends of the'invention with goodresults. However, such materials are preferably added in minorquantities, say from 0.5% to 20%. by weight, and in no event should thesuch added matter exceed about 40% by weight. p

' Theinvention claimed is: 7

1. A new composition of matter consisting essentially of amicrocrystalline wax having an oil content of less than 5% and from0.05% to 1.5% by weight ofa pour depressant prepared by condensingchlorinated: paraffin wax with a material selected from the groupconsisting of naphthalene, toluene, benzene, phenol, phthalic anhydride,aniline, xylene, ethyl benzene, cresol, and methyl naphthalene.

2. A new composition of matter consisting essentially of amicrocrystalline wax having a melting point of above 135 F., a viscosityof at least 65 SUS at'2l0" R, an oil content of not greater than about2% by weight and from 0.05% to 1.5% by weight of the condensationproduct of a derivative of paraffin wax anda material selected from thegroup consisting of naphthalene, toluene, benzene, phenol, phthalicanhydride, aniline, xylene, ethyl benzene, cresol, and methylnaphthalene.

3. Composition according to claim lwherein the selected aromaticcompound is naphthalene.

4. Composition according to claim-f5 1 wherein the selected aromaticcompound is toluene. v 5. Composition according to claim 1 wherein theselected aromatic compound is phthalic 'anhydride. p 6. Compositionaccording to claim 1 wherein the selected aromatic compound is benzene.Y

- 7. Composition according to claim 1 wherein the, selected aromaticcompound is aniline- References Cited in the file of this patent UNITEDSTATES PATENTS 2,045,913 I-Ioy et al. June-30; 1936 2,281,941 Lieber May5, 1942 2,692,835

Capell 0ct. 26, 1954

1. A NEW COMPOSITION OF MATTER CONSISTING ESSENTIALLY OF AMIRROCRYSTALLINE WAX HAVING AN OIL CONTENT OF LESS THAN 5% AND FROM0.05% TO 15% BY WEIGHT OF A POUR DEPRESSANT PREPARED BY CONDENSINGCHLORINATED PARAFFIN WAX WITH A MATERIAL SELECTED FROM THE GROUPCONSISTING OF NAPHTHALENE, TOLUENE, BENZENE, PHENOL, PHTHALIC ANHYDRIDE,ANILINE, XYLENE, ETHYL BENZENE, CRESOL, AND METHYL NAPHTHALENE.